问 princeton mock 上一道题

wtttopUID: 3913556

Since a large number of the ores frequently located in riverbeds are (i)_____on the earth’s surface, where the processing of chemicals is less costly, recovery of underwater ores is not likely to become a (ii)_____procedure.

Blank(i)	Blank(ii)
Ascanty Babundant Cpreserved	Dvaluable Ecost-effective Frejected

选b,e  求大神解答一下，答案的解释没有看懂┭┮﹏┭┮

非常感谢~~~

liufangfangUID: 3465044

这种题已经过时了别做了

wtttopUID: 3913556

liufangfang 发表于 2019-3-7 10:43
这种题已经过时了别做了

请问你是说princeton mock上的题吗？